util.cpp: canonicalize the order of includes

src/util.cpp

@@ -5,13 +5,12 @@
  * See http://opensource.org/licenses/MIT
  */
 
-#include <stdlib.h>
-#include <stdio.h>
-#include <stdarg.h>
-
 #include "util.hpp"
 #include "userland.h"
 
+#include <stdio.h>
+#include <stdarg.h>
+
 void zig_panic(const char *format, ...) {
     va_list ap;
     va_start(ap, format);